Spanish snapdragons in a shallow gene pool
I recently had a discussion with a colleague about the role of
research in practical conservation. We agreed that it is important to know as
much as possible about the biology, for example of threatened species, so that
informed decisions may be made about appropriate measures in conservation.
Thus, data on the genetic structure of populations can inform us about the
origins of that population, the degree of variation within the population and
the relatedness to other populations of the same species. This approach has
been taken by Isabel Mateu-Andrés (Valencia, Spain, pp. 797–804) in a study
of genetic variability (assessed by allozyme patterns for 10 different enzymes)
in two rare and threatened Antirrhinum species:
A. subbaeticum and A. peretgasii. A related but
non-threatened species, A. pulverulentu, was included for
comparison. For the two rare species, the author shows that genetic
variabilities are ‘...the
lowest known for the genus’, whereas in A.
pulverulentum the variability is much greater. Further,
for A. subbaeticum there is
clear evidence for genetic isolation of different populations, with 85 % of the
genetic diversity distributed among the different populations. Overall, these
data conform to the widely acknowledged correlation between population size and
the extent of genetic variability. But what has all this to do with practical
conservation? Firstly, it shows that these threatened species, especially if
individual populations become genetically isolated from each other, have higher
incidences of inbreeding and genetic drift, leading to a lowered evolutionary
potential. Secondly, the data indicate the need for a good germplasm bank for
these species. Thirdly, the author suggests that for A. subbaeticum, with its high
degree of diversity between populations, it is not a good idea to try to
repopulate one region with plants or seeds from another. And, perhaps
obviously, steps should be taken to protect the plants from those factors that
pose the greatest threats.
Professor J. A. Bryant
University of Exeter, UK
j.a.bryant{at}exeter.ac.uk
